1. Field of the Invention
The present invention is directed to a tape cartridge and a tape drive for accommodating an extremely wide tape.
2. Description of the Prior Art
The use of magnetic tape as a medium for data recording has the significant advantages of a relatively low cost and a relatively large recording surface area. Nevertheless, conventional magnetic tape has certain disadvantages associated therewith.
A first of these disadvantages is that tape is a sequential medium, which means that when a data transfer head is located at a beginning of a tape, it is necessary for the tape to be transported along its entire length in order to retrieve (or re-write) information at the end of the tape.
A second disadvantage is that, due to the desire and necessity of storing as much data as possible within an available tape area, the data transfer head technology as well as the recording media technology are pushed to their quality limits.
Moreover, many existing drives and cartridges must be designed within specified form factors, in order to satisfy standardization requirements. As an increasing number of functions become available, which are desired to be accommodated in a drive or on a tape, data storage area or other functions must be sacrificed to accommodate the new, additional functions, or some type of compromise must be reached in the overall design.
Among the more important market requirements which are expected in the near future for data storage on tape is that the need for higher storage capacity will continue to increase, at an even faster rate than previously. As discussed below, for example, the storage capacity of a currently available single cartridge is not sufficient for unattended backup during a longer period of time, and therefore so-called autoloader systems have been developed to automatically insert and remove a number of cartridges in a sequence.
Further market requirements are expected to be a need for faster time to access data, a need for an increased data transfer rate, a lower cost per MB (megabyte) and an overall improved quality and reduced cost.
As noted above, the limited data storage capacity of conventional cartridges has resulted in the development of autoloader systems. Conventional autoloader systems, however, are not a satisfactory solution to the problem of storing a large amount of data in an unattended backup procedure over a relatively long period of time. Several disadvantages exist with regard to currently available autoloader systems.
Because such autoloader systems make use of a large number of cartridges, the cartridges are made relatively small, and therefore have a limited space available for use for data storage. Typically, six to ten of such cartridges must be put in a magazine in order to have sufficient storage area (capacity). Because of the relatively small size of the cartridges, the drive is also made small, in order to match standardized form factors. The drive is disposed in a system housing, which also contains robotics, electronics and software needed for loading an unloading the cartridges.
The relatively large number of components, and therefore the relatively high cost, associated with conventional autoloader systems makes the use of such systems an unattractive alternative for a customer who merely wants long term data backup.
It is an object of the present invention to provide a magnetic tape cartridge, and a drive therefor, which contains a tape having a maximum tape length in a range comparable to the most commonly used high capacity cartridges (LTO, DLT), and which has a minimum tape length in a range comparable to that for conventional fast access cartridges (STK98-40, Magstar, Accellis), but which nevertheless has a data storage capacity which is many multiples more than such conventional magnetic tapes.
The above object is achieved in a magnetic tape cartridge in accordance with the principles of the present invention which accommodates a tape having an extremely large width. The width of the tape in the inventive cartridge can be greater by a factor of six to ten, for example, compared to the aforementioned conventional tapes. The following table compares the inventive tape to several standard formats that are currently in use:
The inventive tape, thus, has a width which is greater than approximately 24 mm, or in a range between approximately 24 mm and approximately 127 mm.
A tape of such an increased width has a tape area available for data storage which corresponds to the respective tape areas of approximately six to ten of the aforementioned conventional cartridges, and thus the storage area available on a single inventive tape cartridge would correspond to the data storage available in a completely filled magazine in a conventional autoloader system. An autoloader magazine completely filled with cartridges contains approximately eight to ten times more parts and components, and therefore by replacing such a magazine with a single inventive cartridge, a considerable cost reduction is achieved.
The inventive drive for operating the inventive cartridge has a form factor which is smaller than, or the same as, the form factor used in a conventional autoloader system. This means there is room to accommodate robust, high quality drive mechanics for accepting the inventive extremely wide tape cartridge. Since only a single cartridge is necessary in order to achieve the same storage capacity as a completely filled magazine in a conventional autoloader system, there is no need to repeatedly load and unload the inventive, wide cartridge, and thus conventional autoloader components such as robotics, control electronics, and control software are not necessary, thereby producing a further cost reduction.
Moreover, in general because the number of parts and components associated with the inventive cartridge and drive is considerably reduced compared to a conventional autoloader system, space is made available for a very robust design, and the quality level will be much higher, and the cost lower, due to the considerable reduction in components.
As noted above, strictly in terms of size, the tape area available for data storage in the inventive cartridge is in the range of a fully loaded DLT/LTO magazine, accommodating approximately eight to ten conventional cartridges. The available data storage in the inventive cartridge will in reality be even larger, however, because in any cartridge the edge effects preclude storage of data at the extreme edges of the tape. In the inventive cartridge, only two such edge regions are present, whereas in a fully loaded conventional magazine accommodating ten conventional cartridges, twenty such edge regions exist.
In any high speed tape drive/cartridge system, a limitation on the mechanical speed at which the tape can be moved exists due to the unavoidable fact that air will be trapped at regions close to the moving tape, thereby producing xe2x80x9ctape lift.xe2x80x9d Due to the increased width of the tape in the inventive cartridge, it is recognized that more air will be trapped than in a conventional cartridge, and this will impose a limitation on the winding speed. Nevertheless, the time to data still will be significantly reduced because there is no need to expend time for robotically loading and unloading one or more cartridges. It is possible to proceed directly to the desired data on the inventive tape. Writing data to completely fill the tape also will be much faster, for the same reason. Moreover, the significantly increased width of the inventive tape allows multiple read/write heads to be disposed and operated in parallel, respectively writing and/or reading in parallel tracks on the wide tape, thereby further increasing the data transfer rate.
The inventive cartridge and drive system also will be more user friendly than a conventional autoloader system, since the inventive cartridge, although wider than a conventional cartridge, still has only one housing, and therefore the overall weight of the inventive cartridge will be significantly smaller than the weight of a fully loaded autoloader magazine. Such autoloader magazines are conventionally made to be transportable, such as by means of a handle attached to the magazine housing, but the weight of a fully loaded magazine consists of the magazine housing itself, plus approximately ten cartridges, each with its own cartridge housing.
Lastly, the inventive cartridge/drive system has the advantage compared to an autoloader system of not requiring robotics and other moving parts, which contribute to acoustical noise in a conventional autoloader system.